HopacLimitr.fsx

#I @"C:\Projects\Lib"

#r "Hopac.dll"
#r "Hopac.Core.dll"

open System
open Hopac
open Hopac.Job.Infixes
open Hopac.Alt.Infixes
open Hopac.Extensions

let get n =
    Ch.create() >>= (fun output ->
        Ch.create() >>= (fun input ->
            Ch.create() >>= (fun count ->
                let disposable =
                    {
                        new IDisposable with
                            member __.Dispose() = Ch.give input () |> run
                    }
                Job.iterateServer n (function
                    | 0 ->
                        printfn "No more tokens"
                        Ch.take input >>% 1
                    | n ->
                        printfn "Still have %d tokens" n
                        Alt.select [
                            Ch.Alt.take input >>%? (n + 1)
                            Ch.Alt.give output disposable >>%? (n - 1)
                            Ch.Alt.give count n >>%? n
                        ]
                )
            )
        )
        >>% Ch.take output
    )

job {
    let! limiter = get 5

    do!
        job {
            printfn "Getting token"
            use! token = limiter
            printfn "Got token"
            do! Timer.Global.sleep <| TimeSpan.FromSeconds 3.0
            printfn "Releasing token"
        }
        |> Job.start
        |> Job.forN 100
}
|> run

async {
    use! token = Async.Global.ofJob limiter
    printfn "Got token"
    do! Async.Sleep 3000
    printfn "Releasing token"
}
|> Async.Start